Conventional paper filters are a random mat of wood pulp fibres, which means pore size varies across the sheet. HIFLUX use lyocell fibre in a woven three-dimensional structure instead, giving a more uniform pore size and more room for fines before the bed chokes. HIFLUX state a flow rate up to 42% faster than standard paper.

Why this matters more on a flat bottom

Flat-bottom brewers spread the coffee in a shallow, even bed, which is the format’s main advantage: water contacts the grounds uniformly rather than migrating through a deep cone. The trade-off is drawdown. Wave filters are thick, the bed is wide, and stalls are common once you grind fine. A faster-flowing filter removes most of that ceiling, so you can grind finer for the same brew time and extract more without the water sitting on top of the bed.

What that changes in the cup

HIFLUX design the pore size to let particles below roughly 20 micrometres through, so a controlled amount of ultra-fines reaches the cup rather than being held back entirely. That adds texture and body. HIFLUX also say the lyocell structure presents less surface area for oils to cling to than pulp paper does, which lets more lipids and the aromatics they carry pass through. In practice, expect a cup with more weight and aroma than the same coffee through a standard wave filter, at the cost of a little of the very clean, stripped-back character some people brew flat-bottom for.

Choosing between 155 and 185

Both sizes use the same material and behave the same way; only the footprint differs, and they follow the standard wave sizing that Kalita established. The 155 is the small format, cut for the Kalita Wave 155 and brewers built on that footprint, and suits roughly 1 to 2 cups. The 185 is the larger format for the Kalita Wave 185 and equivalents, and is the one to pick for batch brews or doses above about 20 g. Match the number on your dripper: unlike a folded cone filter, a wave filter has to sit correctly in the base or the bed will not stay flat.

Specifications

What’s in the box

• 60 × HIFLUX HIGH FAST Wave filters in the selected size